Deterministic Scheduling of Periodic Messages for Low Latency in Cloud RAN

Cloud-RAN (C-RAN) is a cellular network architecture where pro-
cessing units, previously attached to antennas, are centralized in
data centers. The main challenge in meeting protocol time con-
straints is minimizing the latency of periodic messages exchanged
between antennas and processing units. We demonstrate that sta-
tistical multiplexing introduces significant logical latency due to
buffering at network nodes to prevent collisions. To address this,
we propose a deterministic scheme for periodic message trans-
mission without collisions, eliminating latency caused by buffering.
We develop several algorithms to compute such schemes for star-routed
networks, a common topology where all antennas share a single link.
First, we show that deterministic transmission is possible without buffer-
ing when routes are short or network load is low. Under high load,
we allow buffering at processing units and introduce the Periodic
Minimal Latency Scheduling (PMLS) algorithm, adapted from classi-
cal scheduling methods. Experimental results indicate that even at full
load, PMLS finds deterministic transmission schemes with negligible log-
ical latency, whereas statistical multiplexing incurs substantial delays.
Moreover, PMLS runs in polynomial time and scales efficiently to hun-
dreds of antennas. Building on this approach, we also derive low-latency
periodic transmission schemes that coexist with additional random
network traffic. This article extends previous work presented at ICT